Process for the production of high percentage sulfite cellulose



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UNITED STATES PATENT OFFICE.

No Drawing.

To all whom it may con cern Be it known that I, EMILE BRONNERT, a citizen of the Republic of France, residing at 1 Quai du Barrage, in Mulhouse, Alsace orraine, France, have invented certain new and useful Improvements in Processes for Production of High Percentage Sulfite Cellulose, of which the following is a specification.

The present process for 7 is based substantially upon the fact that. the d, prior to the usual boiling with bisu fite, is subjected to a treatment with diluted sulfuric acid, whereby the wood lignin is so decomposed that it is thoroughly dissolved during the subsequent boiling with sulfite lye.

In the manufacture of to Mitscherlich by means of calcium bisulte, or according to Ritter-Kellncr with calcium magnesium bisulfite made from dolomite a certain quantity of incrustation (hemi-celluloses) still remains adherent to he product, which. in contradisti'nction to the pure so-called a cellulose is more or less easily soluble in about 20% alkali.

The cellulose can certainly be successfully freed from a furtherportion of these incrustations if, after running off the sulfite solution, the material be subjected at about 115 C. to boiling with diluted soda solution, caustic soda lye or,better still with a cellulose according sultable mixture of both, pretty much in the same way as Is customary when scalding or securing cotton.

t has also been proposed to em 10y in the first place a. kind of saponification and opening up of the wood substances, generically termed incrustations, by boiling with alkali and then removing the substances still remaining by boiling with sulfite. However the success hereby realized has not met the expectations entertained.

ccording to German specification 237,- 081, in order to obtain cellulose for the production of paper, wood is subjected to a preliminary treatment with very weak causor acid Solution. The selective use Specification of Letters Patent I however v of acids, as

of its weight, whereupon Patented Sept. 27, 1921.

Application filed September 13, 1920. Serial No. 409,976.

acid, not only during the initial but also on boiling, constitutes precisely a sharp difference between that already known process and the present processaccording to which in the first place lixivlation is not effected without pressure,

tic soda or treatment the wood I tion are then first dissolved by the following bisulfite boiling.

According to Willstatter the separation of pure cellulose from incrustations by means of concentrated hydrochloric acid is ust as little suited for technical use upon a large scale.

ccording I another aspect the incrustations of the wood are bound in the substance of ,the wood in a manner. Hence in the manner commonly known glucosides a decomposition of the glucosidelike combination can be effected for example 0.50.7% acid. The lignin separated off ow according to the present process uschas been secured under ut-ilizatlon of the usual manner, by means of diluted about 1% sulfuric acid under pressure, at about 115 (1, the hydrolizing of the different combinations is effected, whereupon the acid is run off for fresh use if necessary, the mass remaining behind being neutralized and, as a second working process, a bisulfite boiling of the usual strength (3-3, 5% S0 is immediately allowed to follow at 120 (1., for instance.

The duration of the new process, be reduced to from two thirds to one half of the time otherwise necessary.

he control of the boiling and the removal of the dissolved stuffs can be hereby effected in the simplest manner.

The progress of the dissolving process can be easily determined by observing the diminution in the percentage of sulfurcus boiling can, by the to an observation made from acid, in the boiling lye also by taking, test Wood material with calcium bisulfite or samples of the cellulose and testing its permagnesium calcium sulfite lye under pres, centage of a-cellulose. sure.

What I claim is In Witness whereof I have hereunto 5 A process for the production of high persigned my name in the presence of two sub- 15 centage sulfite cellulose, characterized by scribing Witnesses. the fact that under low pressure an opening EMILE BRONNERT.. up of the material by boiling with diluted, Witnesses: say 1% sulfuric acid, is allowed to precede L. R. LE SALE, 10 the usual boiling of the already prepared M. SGHLUMBURGER. 

